| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a displacement detecting apparatus can prevent an effect of contaminations deposited on a surface of a glass substrate for example, and detect a displacement of a surface position of its backside with high accuracy. <P>SOLUTION: The displacement detecting device for detecting a displacement of a surface position of a surface 20a to be detected, includes an optical system 3, 4, 5 which guides first to third rays of light L1, L2, L3 to first to third positions respectively to form first to third focal points on the surface to be inspected or in its vicinities, and is common to the first to third rays of light, and a detection system (DS: 5, 4, 3, 6, 7, 8, 9) for respectively detecting first to third pieces of displacement information at the first to third positions based on the first to third rays of light reflected by the surface to be inspected, and detecting the displacement of the surface position of the surface to be inspected based on two pieces of displacement information the most similar to each other out of the three pieces of displacement information. <P>COPYRIGHT: (C)2010,JPO&INPIT |
